ZombiU walkthrough, Part Twenty-Two: The Remaining Letters of Dee
You've survived the brutal Arena and you're back at the Safe House. You don't seem to have any mission now beyond getting the remaining Letters of Dee and delivering them to Dr. Knight. And, with the technology you now have, this shouldn't be a huge problem - though it will require backtracking. Check the terminal in the Safe House to find out where they all are, then go hunting.
You should already have this Letter of Dee. If you missed it, though, return to the small room where you originally found the C4, just inside the sewer beside the swamp. Dee Letter 2 is on the body.
Brick Lane Flats
Return to the flats via the manhole, but backtrack to the warehouse before the flats. You'll emerge from the office with the hole in the ceiling on the bottom floor of the warehouse, and across from the office is a debris mound. Blow it up to find a red zombie on a toilet. Kill it before it can get up and loot its body for a Firing Speed Upgrade, and check the wall for Handgun Bullets.
Take the ladder in the corner of the room up to the hole in the wall leading into the larger warehouse. Be ready - there will almost certainly be two or three zombies waiting to greet you up here. Once you're safe, head into the two-part office with the security door. Head into the office opposite this and look through the glass on the right side of the partition between the two rooms. You'll notice that the Ravens symbol on the far wall, above the locked door, lines up with black smears on the glass. You must line yourself up exactly right in order to scan the far wall and get the code for the door. Do this, open the door, and check the body inside for an Mp5 SD Sub-Machine Gunand Dee Letters 3. The box next to the body also contains Shotgun Ammo, Handgun Ammo and a Capacity Upgrade.
Brick Lane Markets
This second letter is fantastically easy to both get and miss. Leave the manhole and head out onto the first street you ever experienced in ZombiU. Kill any zombies here, then look at the building on the left side of the street, where you scanned your first CCT junction box. Under the stairs leading to the abandoned apartment is a pile of debris. Destroy it with C4 and check the next yard over for a body with a Molotov, and Capacity Upgrade and Dee Letters 4.
Head back here through the sewers in Brick Lane Markets (faster than using the manhole) and make your way to the park. Lure the red zombie into one of the Mines in the park for a quick kill if they're still there, steals its Firepower Upgrade, then get rid of any other nearby zombies. When they're gone, hack through the gate in the top-left of the park, kill the zombie in here, then duck through the hole in the wall. Inside you'll find a body with Dee Letters 5. There's also another Upgrade on the ground.
Tower of London
Leave the tower and head to the beach. Get up on the pier and head for the locked offshore island. Hack the lock open and head down the ramp. The open container here is home to a red zombie. Lure it out and blow its head off so you can search. On its body is a Firing Speed Upgrade; to the left of it is an M4 Tactical Shotgun; nearby is a Spread Upgrade; in a container at the rear of the platform are Handgun Ammo and Carbine Ammo; and on the other body here is Dee Letters 6.
Ignore the security door from the manhole and go out the top way, with the busted stairs. Check far to your left and you'll see a red zombie wandering around. Get its attention with some long-range weaponry, then kill it from the safety of your platform when it runs over. Steal the Spread Upgrade from its body.
The field between here and the nursery will almost certainly have zombies, but it's a big enough area that you can easily hack the door on the shed to the right of the nursery from a great distance. Do so, kill any zombies you must along the way, then check inside for a Capacity Upgrade, a Magnum Pistol and Dee Letters 7 on the body. (No, you don't have to go back into the creepy nursery. Lucky you.)
That's the lot! You can head back to Buckingham Palace and set the final cogs of ZombiU into motion.
Point of no return
This is it. You're closing in on the end of your zombie journey. It's been a long road - and the rest isn't much easier. Areas will soon be closed to you, and if you're short on ammo... well, suffice it to say that you'll want plenty of ammo. Before you deliver the Letters of Dee to Dr. Knight, canvas previous areas for new zombies to kill, and keep your eyes open for ammo stores you might previously have missed.